1. Field of the Invention
This invention relates to conversion of cored rolls to more efficient drilled rolls in which the roll temperature is controlled by fluid circulated adjacent the working surface.
2. Description of the Prior Art
As shown in U.S. Pat. No. 2,890,026 to Marganski et al it is known to control the temperature of the working surface of a roll by circulating fluid through passages in the roll closely adjacent to the working surface. The fluid usually enters a central bore and is distributed to one end of each of a set of connected passages. By a suitable baffle means in the central bore, the fluid is directed through an outlet. The advantages of such temperature controlled rolls are well known and include the ability to precisely control a high rate of heat transfer between the working surface of the roll and material being processed. This results in a more efficient roll operation and a higher degree of smoothness and gloss when used, for example, in a paper calendar. In the past such as before 1960 it was common to circulate temperature control fluid in rather large cores or bores centrally located in rolls. However, the heating or cooling temperature of the fluid was transmitted to the working surface of the roll through the substantial thickness between the core and the surface. Reducing such thickness to improve heat transfer would have substantially changed the flex characteristics of the roll. With the advent of the so-called "drilled roll" of the above patent the cored rolls were acknowledged to be less efficient. While a solid roll easily could be drilled adjacent the periphery and bored along the roll axis for conversion to the more efficient roll, it was impractical to convert the cored rolls. Thus, many less efficient cored rolls remain in production or are scrapped and replaced with a costly new "drilled roll".
Thus, it is an object of the present invention to convert cored rolls to "drilled rolls" in a manner which has been estimated to be approximately one-half the cost of a new drilled roll.